Subject: RE: [ecasound] need some buffering advice
From: Kai Vehmanen (k_AT_eca.cx)
Date: Thu Sep 18 2003 - 02:36:47 EEST
On Wed, 17 Sep 2003, Jamie Lutch wrote:
> ecasound -f:s32_le,2,96000,i -i
> alsa,hw:PDAudioCF -z:intbuf -f:s24_le,2,96000,i -o test.wav
[...]
> 1. in the syntax I am running above, am I correct to assume that the engine
> is reading 32bit from the soundcard (bottom 8 are zeros), then it just
> truncates the 8 zero bits before writing to disk? there is no dithering or
> digital processing going on, right?
No dithering, but the data is converted from 32bit integers to 32bit float
and then back to 24bit integers.
> 2. in the case I need to use -z:db, 100000, I am confused by this statement:
[...]
> "The default is'-z:nodb,100000', which is 100000 samples of buffering
> per non-realtime audio object (files, pipes, etc). For 32bit, 2ch audio this
> means 0.8MB of buffering per audio object... in other words quite a lot."
[...]
> so 100000 samples of buffering is not the same as 100000 samples,
> apparently. it seems from your statement that a 'sample of buffer' is 8KB.
> is this fixed, or is it a function of the soundcard buffer size?
Why do you say that? 0.8MB equals to 820kB, which is hundred times more
than 8kB. Hmm, so -z:intbuf/-z:nointbuf and -b:X options control buffering
for audio devices while -z:db,X for files.
-- http://www.eca.cx Audio software for Linux!
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